In motor vehicles, it is common practice to employ one or more door jamb switches. These switches include a switch element that is shifted between switching conditions when the vehicle door is opened and closed. An outwardly extending plunger is extended when the door is opened and is depressed when the door is closed. Due to dimensional variations the distance between the inner face of the door and its matching door jamb is different from door-to-door. To compensate for this condition, self-adjusting door jamb switches, as shown generally in U.S. Pat. Nos. 3,249,727 and 3,251,971, have been commonly employed by the automotive industry. These switches have a collapsible plunger or other arrangement which self-adjusts upon the initial closing of the door against the jamb after the switch has been assembled. Thereafter, the switch operates in accordance with this initial adjustment. These self-adjusting door jamb switches each have a plunger formed from plastic material which is reciprocated in a metal mounting sleeve fixed onto the door jamb.
When the door of a vehicle is closed, moisture often accumulates and moves along the jamb surface. There is a tendency for such moisture to work its way into the plunger mounting sleeve. This moisture can ultimately cause corrosion, arcing and other damaging conditions at the switch element. Several attempts have been made to overcome the tendency of water to migrate or flow into the mounting sleeve of the adjustable door jamb switch and cause damage over long periods. The most common arrangement is the use of a plastic, flexible boot around the plunger to provide a physical seal between the movable plunger and the inner workings of the door jamb switch. This boot is repeatedly flexed during operation of its door jamb switch and is expensive and can deteriorate over long periods of time. The cost factor is magnified by the volume of switches employed in the automotive industry. Thus, there is a need for a less expensive arrangement or structure for preventing migration of moisture into the switch portion of the door jamb switch used in the automotive industry. More particularly, there is a need for an arrangement to prevent this moisture migration in self-adjusting type of door jamb switches so that the arrangement for preventing migration does not affect the self-adjusting feature of the door jamb switch and/or require additional manipulative and assembly processes.